Reprogramming of somatic cells is a valuable tool to understand the mechanisms of regaining pluripotency and further opens up the possibility of generating patient-specific pluripotent stem cells. Reprogramming of mouse and human somatic cells into pluripotent stem cells, designated as induced pluripotent stem (iPS) cells, has been possible with the expression of the transcription factor quartet Oct4 (also known as Pou5f1), Sox2, c-Myc, and Klf4. Considering that ectopic expression of c-Myc causes tumourigenicity in offspring and retroviruses themselves can cause insertional mutagenesis, the generation of iPS cells with a minimal number of factors may hasten the clinical application of this approach. Here, we show that adult mouse neural stem cells express higher endogenous levels of Sox2 and c-Myc than embryonic stem cells, and that exogenous Oct4 together with either Klf4 or c-Myc are sufficient to generate iPS cells from neural stem cells. These two-factor (2F) iPS cells are similar to embryonic stem cells at the molecular level, contribute to development of the germ line, and form chimeras. We propose that, in inducing pluripotency, the number of reprogramming factors can be reduced when using somatic cells that endogenously express appropriate levels of complementing factors.
Pluripotent stem cells induced from adult neural stem cells by reprogramming with two factors.
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View SamplesIn pluripotential reprogramming, a pluripotent state is established within somatic cells. In this study, we have generated induced pluripotent stem (iPS) cells from bi-maternal (uniparental) parthenogenetic neural stem cells (pNSCs) by transduction with four (Oct4, Klf4, Sox2, and c-Myc) or two (Oct4 and Klf4) transcription factors. The parthenogenetic iPS (piPS) cells directly reprogrammed from pNSCs were able to generate germline-competent himeras, and hierarchical clustering analysis showed that piPS cells were clustered more closer to parthenogenetic ES cells than normal female ES cells. Interestingly, piPS cells showed loss of parthenogenetic-specific imprinting patterns of donor cells. Microarray data also showed that the maternally imprinted genes, which were not expressed in pNSCs, were upregulated in piPS cells, indicating that pluripotential reprogramming lead to induce loss of imprinting as well as re-establishment of various features of pluripotent cells in parthenogenetic somatic cells.
Generation of parthenogenetic induced pluripotent stem cells from parthenogenetic neural stem cells.
Sex, Specimen part
View SamplesMany studies have already shown the reprogramming of somatic cells into other cell types such as neural stem cells, blood progenitor cells, and hepatocytes by inducing combinations of transcription factors. One of the recent development in cellular reprogramming is the direct reprogramming, that can change cell fate towards different lineages. This strategy provides an alternative to the use of pluripotent stem cells ruling out the concerns of tumorigenicity caused by undifferentiated cell populations. Here, we generated induced oligodendrocyte progenitor cells (iOPCs) from mouse fibroblasts by direct reprogramming. The generated iOPCs are homogenous, self-renewing, and multipotent. Once differentiated, the somatic stem cells exhibit morphological and molecular characteristics of oligodendrocyte progenitor cells (OPCs). Thus, we demonstrated that terminally differentiated somatic cells can be converted into functional iOPCs by induction of transcription factors offering a new strategies to cure myelin disorders.
Oct4-induced oligodendrocyte progenitor cells enhance functional recovery in spinal cord injury model.
Specimen part
View SamplesGraphene has been selected as a candidate for synthetic feeder-free culture substrate guiding human/mouse multipotent stem cell lineage specification, and culturing pluripotent stem cells in a number of studies. However, conventional graphene is not an ideal biomaterial to maintain the pluripotency of human pluripotent stem cells (hPSC) including hESCs/hiPSCs due to its intrinsic hydrophobicity and relatively flat surface topography. Here, we applied morphology-controlled nanocrystalline graphene (NG) coating onto the culture substrates via diffusion-associated synthesis (DAS) process and cultivated hPSCs. It is found that enhanced hydrophilicity and controlled surface roughness of DAS-NG enabled tight focal adhesion of hPSCs onto the DAS-NG coated culture substrate and retained pluripotency for over 2 weeks. It is also found hPSCs grown on DAS-NG shared comparable global gene expression profile with hPSCs grown on mouse embryonic fibroblast (MEF). Importantly, the similarities in cell adhesion gene expression between hPSCs grown on DAS-NG and hPSCs on MEF suggest DAS-NG may provide comparable physical cues with MEF for sustaining pluripotency. Taken together, our findings show a new reliable method for culturing hPSCs in feeder-free condition using DAS-graphene.
Establishment of feeder-free culture system for human induced pluripotent stem cell on DAS nanocrystalline graphene.
Specimen part, Cell line
View SamplesThe four transcription factors Oct4, Sox2, Klf4, and c-Myc can induce pluripotency in mouse and human fibroblasts. We previously described direct reprogramming of adult mouse neural stem cells (NSCs) by Oct4 and either Klf4 or c-Myc. NSCs endogenously express Sox2, c-Myc, and Klf4 as well as several intermediate reprogramming markers. Here we report that exogenous expression of the germline-specific transcription factor Oct4 is sufficient to generate pluripotent stem cells from adult mouse NSCs. These one-factor induced pluripotent stem (1F iPS) cells are similar to embryonic stem cells in vitro and in vivo. Not only can these cells be efficiently differentiated into NSCs, cardiomyocytes and germ cells in vitro, but they are also capable of teratoma formation and germline transmission in vivo. Our results demonstrate that Oct4 is required and sufficient to directly reprogram NSCs to pluripotency.
Oct4-induced pluripotency in adult neural stem cells.
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Rapid and efficient generation of oligodendrocytes from human induced pluripotent stem cells using transcription factors.
Specimen part
View SamplesWe demonstrate that the induction of three transcription factors (SOX10, OLIG2, NKX6.2) in hiPSC-derived neural progenitor cells (hiPSC-NPC) is sufficient to rapidly generate O4+ oligodendrocytes with an efficiency of 60 to 70% within 28 days.
Rapid and efficient generation of oligodendrocytes from human induced pluripotent stem cells using transcription factors.
Specimen part
View SamplesThe pathogenesis of acne has been linked to multiple factors such as increased sebum production, inflammation, follicular hyperkeratinization, and the action of Propionibacterium acnes within the follicle. 13-cis Retinoic Acid (13-cis RA, isotretinoin) is the most potent agent in acne treatment. Surprisingly, its mechanism of action in acne is still unknown. Gene expression profiling of cultured human immortalized sebocytes (SEB-1) treated with 13-cis RA was performed to gain insights into its sebocyte-specific mechanism of action. SEB-1 sebocytes were cultured with 0.1 uM 13-cis RA for 72 hours or vehicle control. Gene array expression profiling was conducted using Affymetrix HG-U95Av2 arrays in order to examine changes in gene expression as a result of treatment. A total of 85 genes (78 different genes) were significantly influenced by 13-cis RA: 58 were upregulated and 27 were down-regulated. There were changes in several genes involved in apoptosis and innate immunity. These studies are the first describing the sebocyte- specific response in gene expression associated with isotretinoin therapy and are valuable in identifying potential therapeutic targets in acne.
Neutrophil gelatinase-associated lipocalin mediates 13-cis retinoic acid-induced apoptosis of human sebaceous gland cells.
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View SamplesThe pathogenesis of acne has been linked to multiple factors such as increased sebum production, inflammation, follicular hyperkeratinization, and the action of Propionibacterium acnes within the follicle. 13-cis Retinoic Acid (13-cis RA, isotretinoin) is the most potent agent in acne treatment. Surprisingly, its mechanism of action in acne is still unknown. Gene expression profiling of skin from 8 patients treated with isotretinoin was performed to gain insights into its mechanism of action. Skin biopsies were obtained from the patients at baseline and at 8 weeks isotretinoin treatment. Gene array expression profiling was conducted using Affymetrix HG-U133A 2.0 arrays in order to examine changes in gene expression as a result of treatment. After treatment, 784 genes were significantly changed: 197 up-regulated and 587 down-regulated. The majority of genes that were up-regulated at 8 weeks encode structural proteins of the extracellular matrix such as collagens, fibulin and fibronectin. The preponderance of genes that were down-regulated at 8 weeks are involved in the metabolism of steroids, cholesterol and fatty acids.
Isotretinoin temporally regulates distinct sets of genes in patient skin.
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View SamplesThe pathogenesis of acne has been linked to multiple factors such as increased sebum production, inflammation, follicular hyperkeratinization, and the action of Propionibacterium acnes within the follicle. 13-cis Retinoic Acid (13-cis RA, isotretinoin) is the most potent agent in acne treatment. Surprisingly, its mechanism of action in acne is still unknown. Gene expression profiling of skin from 6 patients treated with isotretinoin was performed to gain insights into its mechanism of action. Skin biopsies were obtained from the patients at baseline and at one-week isotretinoin treatment. Gene array expression profiling was conducted using Affymetrix HG-U133A 2.0 arrays in order to examine changes in gene expression as a result of treatment. After treatment, 43 genes were significantly changed: 38 up-regulated and 5 down-regulated. A significant proportion of these genes are involved in pathways that regulate differentiation, tumor suppression, serine proteases, serine protease inhibitors and solute transfer. These studies are the first describing the initial changes in gene expression associated with isotretinoin therapy and are valuable in identifying potential therapeutic targets in acne.
Neutrophil gelatinase-associated lipocalin mediates 13-cis retinoic acid-induced apoptosis of human sebaceous gland cells.
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